1. Technical Field
This invention relates to a method and arrangement for post preparation of an injection compound which is useable for injection into for instance existing rock cracks or cracks arisen in connection with blasting away rock during for instance tunnel driving, the injection compound having been subjected to a preparation, leading to that the injection compound has been given qualities with regard to the shape of the crack formations of the rock.
2. Description of the Background Art
In spite of the fact that the injection compound has been given qualities in relation to the shape of the crack formations of the rock, problems have appeared to arise with the tightening when injecting the injection compound in the rock This fact depends upon what is happening with the injection compound during the time period passing between the preparation and the injection itself of the prepared compound. In this connection, the following reasons have been able to be verified:
A not desired temperature increase during the preparation in a mixer;
Chemical reactions and viscosity changes after the mixing;
Handling problems during the transfer from the mixer to the pump;
Pressure and streaming problems in the pump and tubes which can result in agglomerate formations, whereby the risk is that big particle agglomerates and for instance ettringite formations will follow into the rock cracks and plug up these ones.
The mentioned problems have been eliminated by the present invention which includes the moment that the injection compound is subjected to a post preparation comprising the step that the injection compound with a flow and a pressure adapted to the same is forced to pass through a wire netting, which has been chosen according to the following criteria:
Assumption of the size of the cracks and cavities in the rock;
The tendency of the injection compound to build up filter cakes;
Desired streaming of the injection compound through the gaps;
The reological qualities of the injection compound.